1. The Field of the Invention
The present invention broadly relates to an improved composite automotive vehicle for use in transporting payloads. In some of its more specific aspects, the invention is also concerned with an improved automotive draft vehicle and/or independent load platform, each of which is especially adapted for use as a component in the composite automotive vehicle. In still other aspects, the invention is concerned with a method of constructing and using the aforementioned composite automotive vehicle, automotive draft vehicle and/or independent load platform.
2. The Prior Art
The payload capacity of automotive vehicles of the type normally carrying the entire payload have inherent restrictions. The payload is supported entirely upon the integral suspension system and in such instances the weight must not exceed the design limitations. Additionally, the steering and handling characteristics tend to change as the payload is increased and often are adversely affected very markedly as the maximum payload design limitations are approached.
The composite method of transporting payloads is intrinsically much more efficient than where the payload is totally carried by the vehicle. This concept is based upon a composite arrangement which includes an automotive draft vehicle such as a truck tractor as one component and a conventional semitrailer as the second component. The resultant composite rig is one in which the total payload capacity is only partially carried by the truck tractor and the balance is supported on the semitrailer and is pulled. The ratio of the total payload capacity to the availabile horsepower rating for the truck tractor is greater when using a composite rig and the efficiency is much higher. However, composite rigs have a number of disadvantages when compared with a singular form truck. The steering and drawing characteristics of a composite rig are much different and are generally considered to be less desirable. The semitrailer does not tag true behind the drive wheels of the truck tractor and special driving techniques are required. There is also a tendency for the composite rig to "Jack-knife" under certain conditions and thus safety considerations usually favor the singular form truck.
It has been proposed heretofore to increase the payload capacity of a singular form truck by extending the length and adding a second drive axle and a suspension system and wheels therefor immediately behind the first drive axle. This proposal has not proved to be entirely satisfactory. The increased payload still must be totally carried by the integral suspension system and the disadvantages noted above for vehicles of this type apply. There is a further disadvantage when the resultant three-axle truck is used to transport a heavy payload over unlevel surfaces. In such instances, the weight of the payload is not distributed evenly between the axles and there is a tendency to overload at least one axle and its integral suspension system beyond the design limitations.
It is apparent from the foregoing that it would be very advantageous to provide an improved composite automotive vehicle for transporting payloads which has all of the desirable features and capabilities of singular form trucks and composite rigs, while avoiding the undesirable features and disadvantages. However, a vehicle having these characteristics was not available prior to the present invention.